Automatic machines for perforating sheets of material are known in the art. Perforation processes are used to make sheets of material breathable or to give a specific aesthetic look to the material. For example, in the leather industry, producing incisions or perforations that create a well-defined geometric pattern on the surface of the product (e.g., automobile seat cover) may be desired.
Conventional perforation machines typically include a conveyor belt that unwinds between two rollers placed at opposite sides of the machine and upon which the sheet of material to be perforated lays. The conveyor belt feeds the sheet of material through a punch tool and die assembly mounted to a tool saddle. The machine controls the punch tool and saddle to repeatedly perforate the sheet of material as it is translated through the machine by the conveyor belt. However, such perforation machines are limited by the fixed size and spacing relationship of the punch tooling, which reduces the ability to customize the perforation patterns on the sheet of material. Moreover, punching through a soft sheet of material often fails to provide a clean cut, resulting in excess undesirable material remaining attached to the sheet of material.
Alternatively, perforation dies can be used to perforate sheets of material. Typically, perforation dies include a lower die plate having an array of punches arranged above the die plate that define a perforation pattern. In use, a sheet of material is placed on the punches of the lower die plate and the sheet is pressed downward onto the punches using a press so as to perforate the sheet of material. A cutting pad is often placed between the sheet of material and the roller press. However, these conventional perforation dies are often not equipped with a proper mechanism for securing a sheet of soft material to reduce the deflection of the material during the punching and unloading process. Thus, when these perforation dies are utilized, the soft sheets of material stretch and/or deform, which results in non-uniform perforation patterns in the material. In addition, the perforation dies can be difficult and costly to manufacture and have fixed perforation patterns, limiting the ability to quickly make complex, variable, and custom patterns.
Therefore, a need exists for a perforation system that reduces the above identified inefficiencies and costs of perforating soft sheets of material.